The use of side airbags is widespread in vehicle technology. Such side airbags serve to protect the occupant to whom they are allocated in the case of a side impact or in the case of an accident in which the vehicle rolls over. For this function, the side airbag is arranged in or on the side bolster of the backrest of the motor vehicle seat or in the lateral structure of the motor vehicle, and in the case of an accident expands between the occupant and the vehicle structure, generally resting against the vehicle structure. The side airbag has a ventilation opening, so that, on impact of the occupant, gas can escape from the interior of the airbag through this ventilation opening and thereby impact energy is dissipated. Absent such a ventilation opening, the occupant would rebound back into the interior of the vehicle from the impact surface of the side airbag, which of course is not desired.
The problem exists that with given airbag volume and with given gas generator output, the size of the ventilation opening would have to be tuned in relation to the weight of the occupant, in order to achieve an ideal protective effect for the respective occupant. In the case of a heavy occupant, the ventilation opening would have to be relatively small, so that the side airbag remains relatively hard and the occupant is prevented from striking through onto the vehicle structure. In the case of a light occupant, the ventilation opening would have to be relatively large, in order to make the side airbag softer.
To solve the problem which has just been mentioned, U.S. Publication No. 2005/0184493 A1 proposes providing a first ventilation opening in a side wall of the side airbag, namely in the side wall pointing towards the inside, which also forms the impact surface. The position of this ventilation opening is selected so that it is covered by the shoulder region of a tall occupant, but is not covered by the shoulder region of a short occupant. If a tall, and hence generally heavier, occupant strikes onto the side airbag, the shoulder region blocks or throttles the ventilation opening and the side airbag remains accordingly hard. If, on the other hand, a short, and hence generally lighter, occupant strikes onto the impact surface of the side airbag, then this ventilation opening remains open and the side airbag shows a correspondingly soft behaviour. An adaption of the ventilation therefore takes place as a function of the size of the occupant.
A disadvantage here is firstly that the ventilation opening must be hit relatively precisely, in particular even when the occupant is not in his standard sitting position (out of position). A further disadvantage is that the adaptation of the ventilation takes place substantially “digitally”, which means that the ventilation is either open or closed. Graduations lying therebetween are relatively difficult to realise.